Evolution in the treatment landscape of non-small cell lung cancer with ALK gene alterations: from the first- to third-generation of ALK inhibitors.

INTRODUCTION: The medical treatment of non-small cell lung cancer (NSCLC) has radically changed over the last 10 years thanks to new molecular-targeted drugs able to act on biological mechanisms involved in tumor development. One such mechanism is the aberrant anaplastic lymphoma kinase (ALK) activation: patients with ALK-driven NSCLC benefit from treatments that selectively inhibit its pathogenetic mechanism. Areas covered: The first-generation ALK inhibitor is crizotinib, initially used in Europe as second-line treatment for ALK-positive metastatic NSCLC patients, then approved as the standard first-line (already approved in the USA as front-line therapy). However, most patients eventually experience disease progression due to the emergence of secondary resistance, partly linked to ALK-dependent mechanisms, hence the development of second- and third-generation ALK inhibitors: ceritinib, alectinib, and brigatinib are approved for ALK-positive NSCLC, lorlatinib is currently being evaluated while others are under development. Expert opinion: Despite the considerable responses to these new inhibitors, however, resistance mechanisms are described. Thus, while the therapeutic scenario of NSCLC has been soon revolutionized introducing next-generation ALK inhibitors in the first-line setting, future research should identify combined therapies or new generation drugs overcoming resistance in pretreated patients.